Bitcoin and Ethereum will eventually go to zero. The immediate instinct upon seeing this is to call it a fool. Don't worry, you can extend the time scale and look at it for 200 years. After 200 years, if it's still gold, gold will definitely continue to rise because it's a real thing and really scarce. Two hundred years later, Bitcoin and Ethereum will return to zero. Either better digital currencies will be designed, quantum computers will crack them, or the foam will burst and no one will play.